Exploring sanitation in postwar Los Angeles, this article argues that as white voluntary groups formed task forces to clean up the city, they endangered Mexican and black Angelinos by endorsing solutions to urban welfare defined by antistatism and carceralism. I read these activities through the lens of white ignorance, whereby white Americans elaborated folk knowledge of successful urbanism on their own terrain and terms, which had no capacity to attend to other classes and races. I treat white ignorance not as a cognitive defect or proxy for innocence, but rather as a structural condition of postwar urban political economy.